I agree that experience is gathered in any particular theatre, however due to the laudable improvements in engineering and standards worldwide, that experience gathers in a glacial manner in the airline world.
Experience is gathered not from seeing the same thing a million times (though more than once is a benefit) so much as how many things you see.
During my time in an airline I was taught about many emergencies by instructors who were excellent in technique but had no experience of said emergency.
The reality of engine failures/fire, smoke in the cockpit, decompression, bird strike, death on board, diversions etc are never the same as potted exercises.
I also noticed that the quality of those I flew with bore no relation to their hours.